The present invention is directed to an integrated circuit (IC) and, in particular, to monitoring signals inside the IC so as to diagnose various conditions which might be occurring. IC's are extremely dense with circuitry, and contact pads through which one might access such circuitry are at great premium. As an example, an IC with which the present invention has been used measures 1.4 cm square and has over 300 connecting pads on its edges. These contact pads are dedicated to various circuit points inside the IC. It has been found to be of great advantage to be able to access, through existing contact pads, circuit points in the IC not heretofore monitored for lack of access through available contact pads.